1. Field of the Invention
The present invention relates to a communication apparatus.
2. Description of the Related Art
Conventional communication terminals always accept incoming calls to start communication in most cases.
If, however, a communication terminal is unable to accept communication, e.g., if a facsimile apparatus cannot accept facsimile reception because there is no printing sheet for facsimile reception, the apparatus sometimes rejects or ignores an incoming call.
Also, an incoming call signal transmitted through ISDN contains information such as a calling party number. By effectively using this information, a called communication terminal can make a judgement on whether the incoming call should be accepted or not.
Recently, to meet increased variations of communication lines and communication methods, a new product has been proposed by which only a communication control unit of a communication terminal is constructed and which functions as a communication terminal when the communication control unit is connected through an interface to a main unit (e.g., a copying machine) including an operation unit, a reading unit, a printing unit, a display unit, and the like.
With this product, variations of combinations of the communication control unit and the main unit can be increased by giving versatility to these units and the interface between them. This facilitates providing communication terminals meeting the needs of users.
When a communication terminal is constructed by connecting the communication control unit and the main unit through the interface as described above and a function of making a judgement on whether an incoming call should be responded to or not is imparted to the communication control unit, this communication terminal always accepts incoming calls regardless of the state of the main unit even if no incoming calls can be accepted due to the state of the main unit.
Additionally, it is difficult to prevent direct mails or select specific parties to be called, i.e., it is difficult to make a judgement in accordance with the setting by an operator such as a user on whether an incoming call should be responded to or not.
Also, the state of the main unit such as the presence/absence of printing sheets and the setting by the user can change every moment. However, it is difficult to easily make a judgement in accordance with these changes on whether an incoming call should be responded to or not.
Furthermore, to provide communication terminals meeting various needs of users, it is necessary to realize main units and communication control units, which achieve the above functions and meet the various needs, and interfaces for connecting these units.
When an incoming call arrives at an apparatus connected to an integrated digital communication network, the apparatus makes a judgement on whether the incoming call should be responded to or not in accordance with various factors, e.g., whether the state of the apparatus (e.g., the state of a memory or a printer) allows the call reception or whether the incoming call is a desired incoming call (called party number check). If the apparatus judges that it cannot respond to the incoming call, the apparatus rejects the incoming call (sends a release completion message: REL COMP) or ignores the incoming call (does not respond to the incoming call). The apparatus uniquely determines which operation is to be performed and performs the operation in accordance with the determination.
In the above conventional system, if a plurality of terminals are connected to one ISDN and an incoming call different from a called party number assigned to a certain terminal arrives at the terminal, the terminal judges that it cannot respond to this incoming call and either rejects or ignores the incoming call. Therefore, if the terminal is so set as to reject the incoming call, the possibility of call reception by a terminal by which the incoming call can be accepted is lost. In contrast, if the terminal is so set as to ignore the incoming call, the calling party cannot make a judgement on the reason why the called party does not respond (e.g., because the called part is performing communication or unable to accept the incoming call). Consequently, conditions convenient for the user cannot be set, and this results in inconvenience.
In conventional communication systems, a transmitting side adds secondary information as header information to data to be transmitted and transmits the data to a receiving side. The receiving side can recognize the character of the received data main body in accordance with the secondary information. Hence, the header information is exchanged as important information.
More specifically, when a personal computer is to transmit a certain data file, the computer forms the identification information of the file, e.g., the file name, file number, data type, data size, and file formation date, as the header information of the file and adds this identification information to the file main body.
Also, as shown in FIGS. 15 and 16, a facsimile apparatus adds header information to the leading edge of each page of an image to be transmitted and transmits the image to a partner facsimile apparatus. This header information contains, e.g., the transmission date, transmission time, calling party number, calling party abbreviation, destination abbreviation, page number, and total number of pages.
Since the header information is transmitted as a part of the image data to be transmitted, the header information is developed to have the same coding system and resolution as the image data and added to the head of an image data region. For example, character data corresponding to the header information is read out from a font ROM (Read-Only Memory) of the facsimile apparatus and developed to have the same coding system and resolution as the image data.
That is, when the image data is raw, the font data of the header information is developed into a raw image. When a facsimile coding method such as MH (Modified Huffman) is used, the font data is developed into codes of this coding method. Analogously, when a resolution of 8xc3x973.85 pels/mm as one facsimile resolution is selected, the font data is developed in accordance with this resolution. The header data thus developed is connected as image data to the head of the image data to be transmitted to form final image data, and this final image data is transmitted.
To connect the header image to the head of the image data, the header image is overwritten on a few lines of the image data necessary for the header image, the image data to be transmitted is connected to the header image data and the image data is so reduced that the data can be printed on a fixed-size printing sheet on the receiving side, or a few lines of the image data necessary for the header image are deleted from the trailing edge of the image data.
Recently, to meet increased variations of communication lines and communication methods, a new product has been proposed by which a communication control unit for controlling communications of a communication apparatus is constructed as one functional part and which functions as a communication apparatus when the communication control unit is connected through an interface to a main unit including an operation unit, a reading unit, a printing unit, a display unit, and the like.
With this product, variations of combinations of the communication control unit and the main unit can be increased by clearly separating the communication control unit from the main unit and giving versatility to the interface between them. Consequently, various communication apparatuses meeting the needs of users can be easily provided.
When a communication terminal is constructed by connecting the communication control unit and the main unit through the interface as described above and a function of forming the header information is imparted to the communication control unit, the communication control unit must manage and input data for the header. This not only makes communication control cumbersome but also increases the cost and size of the communication control unit.
It is an object of the present invention to improve a call receiving operation of a communication apparatus constructed by connecting a main unit and a communication control unit.
It is another object of the present invention to accurately make a judgement on whether an incoming call should be responded to or not, without using any complicated arrangement, in a communication apparatus constructed by connecting a main unit and a communication control unit.
It is still another object of the present invention to make a judgement in accordance with a setting by an operator on whether an incoming call should be responded to or not, without using any complicated arrangement, in a communication apparatus constructed by connecting a main unit and a communication control unit.
It is still another object of the present invention to appropriately determine whether an incoming call should be rejected or ignored.
It is still another object of the present invention to improve an arrangement or procedure of adding additional information to transmission data and transmitting the data in a communication apparatus constructed by connecting a main unit and a communication control unit.